1. Field of the Invention
The present invention generally relates to a video camera. More specifically, the present invention relates to a compact video camera with electronic picture stabilizer, in which motion vectors of four (4) blocks within an image field are detected according to a representative point matching method so as to control reading addresses of a field memory.
2. Description of the Related Art
In conventional such a kind of a compact video camera, as disclosed in pages 48-54 of National Technical Report Vol. 37No. 3 June, 1991, a dispersion that is a magnitude of an absolute value of a difference between an average motion vector and a motion vector of each block is evaluated, and an image extracting area, i.e., a reading address of a field memory is determined by multiplying a coefficient according to the dispersion and the average motion vector. A digital video signal of the image extracting area that is read from the field memory is given to an electronic zooming circuit or interpolation circuit so as to be subjected to an enlargement or interpolation, so that a video signal with no instability can be obtained.
In addition, the above described dispersion can be calculated, specifically, according to the following equation. ##EQU1##
aveX and aveY: average motion vector
vectX and vectY: motion vector of each block
n: number of blocks
In the above described prior art, it can be expected that a picture stabilization with accuracy is implemented when the dispersion is small, that is, when no passing object exists in all the blocks in the image field. However, in a case where a passing object enters in a specific block, the dispersion becomes large and an error occurs in the average motion vector, and therefore, it is difficult to implement an effective picture stabilization.